Drum & Bass Drum fills

Just a quick q about drum fills. Im into the tech dnb, critical, symmetry, dispatch kinda stuff, and im trying to figure out how these guys get there drum fills sounding so good. Are they programming them in on there own and building from scratch or are they sampling them from other tracks and chopping/changing the tempo/pitch on them? Cheers for any tips!
Break seems to be the boss at this, a couple of examples below:

To replicate Break your really shooting for the stars. Try sampling your drums messing around with the arrangement and equally as important the velocity, that'll help give the drums, more realism, as a drummer won't hit a drum in the exact same spot with the exact same force every time.

Try sample breaks and take what you think are good parts of them. Recycle is pretty good for this and then layer till its full sounding and not cluttered, tight drums always sounding better then a big mess.